1. Field of the Invention
The present invention relates to inkjet inks, and, more particularly, to inkjet inks having improved jetting in use with high resolution nozzle plate materials.
2. Description of the Related Art
Thermal inkjet printing, to which this invention relates, is a commonly practiced form of printing. Thermal inkjet printing involves intense heating of an aqueous ink in a small amount in contact with a heating element so the ink is vaporized. The vaporized ink, including solids in the ink, is then expelled through a nozzle and subsequently jetted to an intended substrate, such as, for example, paper.
The composition of an inkjet ink is traditionally comprised of deionized water, a water-soluble organic solvent, and a colorant. The colorant may be a soluble dye or insoluble pigment. Traditionally, pigment based inks may have some disadvantages as compared to dye based inks as traditional pigment based inks tend to have slightly higher solids and viscosity which may pose to be more difficult for jetting through relatively smaller nozzle printhead designs. For example, due to the insolubility of pigments in water, polymeric dispersants and/or surfactants are typically added to improve the dispersibility of the pigment. The addition of a polymeric dispersant can increase the viscosity of an ink, and a viscous ink may be more difficult to jet in a printhead.
As inkjet resolution and speed increase, inks need to be more compatible with improved high resolution nozzle plate materials. For example, inks must be formulated to be jetted with high resolution nozzles without causing sag or bulge. Further, the inks should not dry prior to jetting, therein clogging the one or more nozzles. In addition, the inks should not flood under small nozzle diameters, those of about 15 um or less. While being able to conform to the above mentioned issues, the inks should also enable an individual to economically benefit by having a lower cost per page.
What is needed in the art is an economical inkjet ink having high compatibility with high resolution nozzle plate materials.